1. Field of the Invention
The present invention relates generally to data storage devices and particularly to an improved tape leader apparatus for pulling tape from a reel.
2. Background of the Invention
Magnetic tape is frequently used to store digital data. Such tape may be housed in a tape cartridge that protects the tape from damage. Prior to use, the tape from a tape cartridge, which is the supply reel, must be connected to an empty drive reel which will act as a take-up reel. The tape may then be transferred from the supply, or cartridge, reel to the drive reel during use. In order to transfer tape from the supply reel to the drive reel, there must be a mechanism for attaching the tape from the cartridge reel to the empty drive reel.
There are currently two commonly used methods for coupling the tape from the cartridge reel to the drive reel. One method is to use a tape leader block. A leader block is attached to a free end of the tape and is used to withdraw the tape from the cartridge for read/write operations. A threading mechanism, such as a threading or loading post or arm, grabs the leader block and pulls it from the cartridge. The threading mechanism then pulls the leader block through the tape path which includes a series of guide posts or bearings, across a longitudinal read/write head, and into a slot in a take-up reel.
The leader block and take-up reel are precisely manufactured so that when the leader block is inserted into the slot in the take-up reel, the slot is sufficiently closed by an end of the leader block to create a relatively smooth surface on the hub of the take-up reel. Ideally, the leader block should cover the slot such that the interface between the end of the leader block and the hub is perfectly smooth. Such a perfectly smooth interface, however, is not practical to manufacture. Therefore, small discontinuities between the leader block and the hub are always present. Such discontinuities can cause impressions in the first wraps of the tape around the hub. These impressions may affect the ability to retrieve data stored on the tape, which results in data errors. To ensure data integrity, a known practice involves not writing data to the portions of the tape having impressions. For example, if the first 100 wraps of the tape are typically affected by tape impressions, then no data is stored on the first 100 wraps of the tape. Such a practice, however, results in wasted data storage capability and wasted time. When the tape path is long with many turns and tight spaces as is typical in many modern tape drives, the threading mechanism required for the tape leader block method would be very complicated and costly.
A second method for threading the tape from the cartridge reel to the drive reel is to use a two-leader method, one tape leader on the cartridge reel and one tape leader on the drive reel. The drive then connects the two leaders and winds them onto the drive reel. The tape is then pulled by the connected leaders from the cartridge reel onto the drive reel. A first tape leader is formed at the free end of the tape, which is on the cartridge reel. A second tape leader is connected to the drive reel. According to one prior art method disclosed by U.S. Pat. No. 4,572,460, the first tape leader has an enlarged flat tab supported by a stem portion. The tab is flat in the same plane as the tape and is flush with the tape. The second tape leader has a locking aperture at one end through which the enlarged tab can pass or be pushed.
This prior art method does not reliably make the connection coupling the two leaders together. Further, the connection between the leaders, once made, is not very strong and may result in the leaders disconnecting improperly during use.
Therefore, the current technology would be improved by providing an improved tape leader apparatus for pulling tape from a reel.